Browsing by Author "Amiyangoda, A.G.T.R."

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    Investigation on Structural Modification of Sri Lankan Vein Graphite for Ion Intercalation
    (Uva Wellassa University of Sri Lanka, 2015) Amiyangoda, A.G.T.R.; Rathnayake, R.M.N.M.; Karunarathne, R.I.C.N.; Wijayasinghe, H.W.M.A.C.
    Rechargeable batteries have become the main energy source for the portable electronic devices. Synthetic graphite have been used as anode electrode material in rechargeable batteries. Presently these rechargeable batteries are expensive mainly due to high cost of materials, such as synthetic graphite and metal oxides, used in their electrodes. It is suggested that the cost of these batteries can be reduce by introducing cheaper natural graphite for their anode electrode. Sri Lankan natural vein graphite can be classified into four distinct structural verities. They are Shiny-Slippery- Fibrous Graphite (SSF), Needle-Platy Graphite (NPG), Coarse Striated-Flaky Graphite (CSF) and Coarse Flakes of Radial Graphite (CFR). Development of Sri Lankan natural vein graphite to the anode of Li-ion rechargeable batteries, through purification and surface modification have been investigated recently. Furthermore, natural graphite has to be structurally modified by expanding interlayer distance to facilitate the intercalation of larger Na ions for the application in rechargeable Sodium Ion Batteries (SIB) (Wei, 2011). The present study investigated the possibility of expanding the interlayer distance of Sri Lankan natural vein graphite for accommodating Na-ion intercalation by converting into Graphite Oxide (GO). Materials and methods Purified samples from all four structural varieties of Sri Lankan vein graphite, were used in this study. Raw graphite samples were oxidized to Graphite Oxide (GO) by using improved hummers method (Madusanka Y.N., Amareweera T.H.N.G.,Wijayasinghe H.W.M.A.C., 2013). In this method 96% H2SO4 (Sigma-Aldrich) and 85% H3PO4 (Sigma-Aldrich) were added to purified vein graphite. Then KMnO4 (Belgolabo) was added little by little to the mixture with in two hours and stirred. Sample was allowed to cool until room temperature. Solution was poured into 30% H 2O2 in an ice bath and the sample was vacuum filtered using Fisher brand filter papers using distilled water. The d.c. electrical conductivity of raw graphite and prepared GO samples were measured using the standard four probe method. Fourier Transform Infrared (FTIR) spectra of raw graphite and GO samples were employed to study the structural modification. Further the X-ray diffractometry was used to confirm the formation of GO.For the Na-ion intercalation study, the modified graphite oxide was tape casted by the doctor blade method to fabricate electrodes. GO was the active material, carbon black was selected as the conductive additive and the binder was polyvinylidene fluoride (PVDF). All the materials were weighed using a chemical balance and placed in a small beaker. Then excessive amount of acetone and dimethylformamide (1:1 ratio) were added to the beaker, covered with an aluminum foil and stirred for 12 hours. Mixture was poured on to a copper foil pasted on a glass to form a very thin layer. It was allowed to dry. The electrodes were fabricated by cutting the copper foil to required shape. A half-cell was assembled using the fabricated GO anode with a gel electrolyte and sodium metal as the reference electrode. Assembling and testing of the cell was conducted inside a N2 filled glove box. Discharging current of the half-cell under 0.5 kΩ load over time was measured and it was recorded using a computer interfaced program.
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    Investigation on Structural Modification of Sri Lankan Vein Graphite for Ion Intercalation
    (Uva Wellassa University of Sri Lanka, 2014) Amiyangoda, A.G.T.R.
    Lithium-ion batteries are now widely used in electronic devices. Li-ion batteries have become the main energy source for the portable devices. Synthetic graphite is used as anode material in Li-ion batteries. Since both synthetic graphite and Li are very costly the Li-ion batteries are presently expensive. Cost of the batteries can be reduced by using Sri Lankan vein graphite for anode. On the other hand, natural graphite can be processed into expanded layer form (structural modification) of GO which is expected to facilitate the intercalation of ions. Therefore intercalation of larger ions is better. So further more cost reduction can be done by using more abundant and less expensive, but larger ions like Nat, Mg2+, etc. To study the possibility to produce such a battery, ion intercalation behavior of GO was investigated in this study. Purified samples from all four varieties of Sri Lankan vein graphite (KSSF, KNPG, KCFR and KCSF) were oxidized to GO by using improved hummers method. FTIR spectra confirmed the successful synthesis of GO. DC electrical conductivity was measured using four probe method and KSSF gave the highest DC electrical conductivity value. A half-cell was fabricated using KSSF GO. Tape casting method was used to make the electrode. A gel electrolyte was used in the cell and sodium metal was used as the reference. Assembling and testing of the cell was conducted inside a N2 filled glove box. Discharging current of the half-cell under 0.5 IS2 load over time was measured and it was recorded using a computer interfacing program. Then discharging current was plotted against the time. GO half-cell gave an O.C.V. of 2.9 V, which indicates the successful intercalation of Na+ ions to GO. Therefore it can be concluded that it is possible to intercalate relatively larger ions like Na+ to structurally modified Sri Lankan vein graphite (GO). Key words — Vein graphite, Graphite Oxide, Intercalation
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    Recycling of Cathode Ray Tube Glasses and Utilizing the Waste Glasses in the Roof Tile Industry of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2018) Jayasinghe, M.N .; Pitawala, H.M.J.C.; Fernando, K.J.R.S.; Amiyangoda, A.G.T.R.; Ehalanrialpe, E.M.T.D.S.B.
    With the development of the technology the Cathode Ray Tube (CRT) monitors are being replaced by modern Liquid Crystal Display (LCD) or Light Emitting Diode (LED) display screens, transforming the used CRT monitors into a major e-waste. CRT glasses contain lead (Pb) as a constituent to an extent of 18% - 22% w/w. The emission of lead to the environment causes numerous harmful effects to the living beings. Sri Lanka has a burden of nearly 140,000 Mt of CRT glasses as e-waste and appropriate measures should be taken to dispose or recycle CRT glass waste. Current study proposes to utilize CRT waste in the roofing tile industry as a glaze or body mix. CRT glass powder was directly mixed with red clay in a range of ratios, while examining the modulus of rupture, water absorption, shrinkage and the amount of lead leaching of the glass powder and red clay mixture. The red clay was procured from the silt deposits in irrigation tanks in North Central Province of Sri Lanka. The best percentage of CRT glass powder, which was added to red clay was determined as 15%. The lead leaching rate of the material corresponds to that ratio of 15% CRT powder into red clay, retained at a rate of 0.94 ppm implying that rate of releasing lead is considerably low and it would not emerge harmful causes to the environment. The addition of CRT glass powder exhibited relatively better vitrification and finishing, depicting the potential to utilize the application in the commercial glass industry. It can be concluded that the waste CRT glasses can be utilized economically as an eco-friendly material in a novel technological way, where findings of the application of waste CRT in Roof Tile Industry. Keywords: CRT glass, Lead, Modulus of Rupture, Red Clay, Glaze, Recycle